1. Field of the Invention
The present invention is generally directed to a fuel reformer which includes a burner forming a flame, a reforming portion surrounding the burner and exhausting a reformed gas, and a heat exchanger establishing heat exchange between the reformed gas and a raw material gas.
2. Description of the Related Art
Referring to FIG. 15, there is illustrated a conventional fuel reformer which is disclosed in Japanese Patent Laid-open Print No. Hei. 9(1997)-153372. This fuel reformer is designed for obtaining hydrogen through steam reforming, from a hydrocarbon such as CH4 or C3H8. In this fuel reformer, a reforming portion K is placed around a burner B which forms a flame. The reforming portion K is connected, by way of a conduit P, to a heat exchanger C so as to establish heat exchange between a reformed gas exhausted from the reforming portion and a raw material gas. The reforming portion K is configured to flow the heat-exchanged raw material gas such that the heat-exchanged raw material gas flows axially upwardly in an inner region, and then in an outer region flows axially downwardly.
In addition, as shown in FIG. 16, a conventional hydrogen containing gas producing device, which is disclosed in Japanese Patent Laid-open Print No. 2000-15501, produces steam by utilizing an exhaust gas of heating the portion K.
The abovementioned fuel reformer is applicable to phosphoric-acid fuel cells (PAFCs) in which steam is easily derived from a cell. On the contrary, there is a problem that the abovementioned fuel reformer is not applicable in solid-state polymer electrolyte fuel cells (PEFCs) in which steam cannot be derived from a cell due to its lower temperature.
In the above fuel reformer, despite the efficiency heat exchange for the reforming portion K, a problem occurs in heat loss due to the connection between the heat exchanger C and the reforming portion K which is established by interposing the conduit P therebetween.
Moreover, in the foregoing hydrogen containing gas producing device, a surface of the reforming portion which is to be heated is flat, resulting in that when the reforming portion is heated by the exhaust gas, the exhaust gas is concurrently released from the opposite side which is covered with a heat-insulating material.
Thus, a need exists to provide a fuel reformer for fuel cells, which is free from the aforementioned drawbacks.